The overall goals of this proposal are to determine (1) the precise chromosomal location of the gene causing Wilson's disease (WD) which we have mapped to chromosome 13 in 5 middle Eastern kindreds using genetic linkage to DNA markers and (2) the extent of genetic heterogeneity for this disorder. In order to accomplish these goals, we shall obtain comprehensive pedigrees from informative families of patients with WD. The diagnosis of WD in all cases will be established accroding to comtemporary research criteria. The largest families available will be selected from among those studied by an international group of collaborators. We shall obtain blood samples from individuals in these families for the preparation of genomic DNA, and in some cases, establishment of parmanent lymphoblastoid cell lines. The banked cell lines will serve as a permanent source of DNA for subsequent molecular analyses. Initially, we will develop a fine-structure linkage map for the relevant regions of chromosome 13 using multipoint linkage techniques. This map will then be used to identify flanking DNA markers which define the smallest co- segregating region (SCR) for the WD locus (WND). Identification of the SCR for WND will enable us to test effectively for genetic heterogeneity in WD and thus determine whether more than one gene can cause this disorder. This knowledge will provide the posibility of reliable presymptomatic, prenatal, and gene carrier detection of members from appropirate families. A paradigm utilizing WND genotype information obtained from linkage analysis could then be used to test genetic and non-gentic models that account for the clinical and biochemical variation in the disorder. Finally, precise localization of the WD gene could effectively lead to the isolation and characterization of the defective gene itself using DNA cloning techniques based on its map location. Characterization of the WD gene sequence and product would lead to an understanding to the basis for the disease and might allow development of an effective therapy without harmful side effects.